Another thing that works is fine meshe screens!
If memory serves me right 100 mesh will filter water from gas and fuel.
My setup is a laboratory graded seive 100 mesh sitting in the bottom of my funnel.
Works like a charm, collects the tiniest little globuals of water.
Believe the principal is that once the mesh is fuel soaked the water drops just can't penetrate due to the 'dissimilar' characteristics of the fluids.
That is also why felt filters work so well.
Aviation used these principals for years, all bush pilots carry either felt cloths or chamois cloths to filter their gas from stashed bbls.
Chamois is preffered to felt because felt can release tiny fuzzy 'hairs' while chamois will not, mind you felt use was very common.
BUT, where in this day or age can one purchase a felt hat?